1. Technical Field
The present invention relates to a liquid discharge apparatus.
2. Related Art
As an ink jet printer that discharges ink and prints an image or a document, a printer that uses piezoelectric elements (for example, piezo elements) is known. The piezoelectric elements are provided corresponding to a plurality of nozzles in a head unit (print head), respectively, and are driven in accordance with drive signals, respectively, and thereby a predetermined amount of ink (liquid) is discharged from the nozzle at a predetermined timing. The piezoelectric element is a capacitive load like a capacitor in terms of electric power. Therefore, a sufficient current needs to be supplied so as to operate the piezoelectric element of each nozzle.
Therefore, in the related art, a configuration is known, in which a source drive signal of the drive signal to be generated is amplified by using an amplifier circuit and the amplified drive signal is supplied to the head unit such that the piezoelectric element is driven. Examples of the amplifier circuit include a system of performing current amplification of the source drive signal by using a class AB amplifier or the like (linear amplification system, see JP-A-2009-190287) or a system of demodulating by using a low pass filter after pulse width modulation, pulse density modulation, or the like of the source drive signal (class D amplification system, see JP-A-2010-114711). In addition, a system of switching a voltage that is applied to a piezoelectric element into a plurality of levels (voltage switching system, see JP-A-2004-153411) is also proposed, in addition to a configuration in which the source drive signal is amplified by using the amplifier circuit.
However, the linear amplification system results in high power consumption and poor energy efficiency. The class D amplification system achieves higher energy efficiency, compared to the linear amplification system, but has a problem of an occurrence of electromagnetic interference (EMI) because high currents are switched at a high frequency. In addition, in the voltage switching system described above, power saving is achieved to some extent, but still has to be improved.